Spherical flange assembly

ABSTRACT

A spherical flange assembly is disclosed. The spherical flange assembly comprises a seat member, a heel member, a seal gland and at least one nut and bold assembly. The seat member includes a concave portion. The heel member includes a convex portion and a seal gland opening. The seal gland is disposed within the seal gland opening.

CROSS-REFERENCE TO RELATED APPLICATION

This invention is a continuation of U.S. patent application Ser. No.10/838,282 filed on May 4, 2004, now U.S. Pat. No. 7,144,049, which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to spherical flange assemblies and, inparticular, to spherical flange assemblies that allow for angularmisalignment without resulting in either large duct loads or jointleakage.

BACKGROUND OF THE INVENTION

Currently, aircraft designers and manufacturers use various flexible,joints throughout the manufacture of the jet engines for use in theaircraft. To this end, various attempts to develop a satisfactoryflexible, moderately pressurized joint have been made.

For example, U.S. Pat. No. 4,448,449, issued to Halling, et al. andentitled “Flexible Piping Joint and Method of Forming Same” (Halling),discloses a fluid-tight coupling and sealing apparatus. Hailingdescribes a flexible piping joint, for use in fluid systems at moderatepressures and temperatures, that require a limited amount of angulationduring operation. The invention in Halling, however, employsstructurally inefficient load paths and non-metallic sealing elements.Further, these elements are not feasible at the extreme temperatures andpressures of rocket engine applications. Moreover, the sealing interfacedepends on the interference fit between the non-metallic seal and themetal duct material, both of which have significantly different thermalcoefficients of expansion which limit the allowable operatingtemperature range. Additionally, the spherical interface must react withthe pressure-separating load with the hoop strength of the concentricrings through a very structurally inefficient contact angle. Thus, forhigh pressure applications, the ring thicknesses would be significant,resulting in a very heavy structure, much larger in diameter for a givenduct diameter.

U.S. Pat. No. 4,772,033, issued to Nash and entitled “Flexible DuctJoint Utilizing Lip in Recess in a Flange” (Nash), discloses a flexuraljoint for connecting opposing ends of two annular ducts. The inventionin Nash is directed towards large diameter thin wall jet engine casingjoints that permit both torsional and transverse motion. The sphericalinterface possesses a much larger diameter than the casing diameter,with the retaining bolt pattern possessing an even larger diameter.However, this type of structurally inefficient interface is also onlyacceptable for low-pressure applications that do not have to react largeseparating loads. For example, in high-pressure applications, theinterface seal must be positioned close to the duct internal diameter tominimize the pressure separating load. Additionally, the interface boltsmust be preloaded at a stiffness level sufficient to preclude separationat the seal interface with the high operating pressures. Thus, theteachings of Nash are not applicable or structurally feasible forhigh-pressure applications.

Finally, U.S. Pat. No. 5,697,651, issued to Fernandes and entitled“Flexible Duct Joint Having a Low Leakage, Pressure-Balanced BellowsSeal” (Fernandes), discloses a flexible joint for sealing two conduits.Fernandes discloses a flexible duct joint for aircraft enginespossessing compressed air ducting joints that operate at relatively lowpressures, as compared to rocket engine joints. The joint conceptpermits angulation motion during operation with limited leakage which isacceptable in the compressed air system. However, Fernandes utilizesjoint structural shapes, retention mechanisms and multi-convolutionbellows that are not feasible for rocket engine high pressure cryogenicand hot gas systems that require zero leakage.

Although the aforementioned references do provide flexible joints toovercome jet engine operating conditions, the references neverthelessfail, in one form or another, to facilitate the much more extremeconditions that exist in a rocket engine. This is primarily due to thefact that the aforementioned references are typically conceived forapplications with operating pressures less than 1000 pounds per squareinch (psi). The references are, generally speaking, not structurallyefficient or feasible enough for applications within the 8000 psi range.

Since the early development of liquid-fuel rocket engines, the need totransfer propellants from low pressure supply tanks to turbopumps,turbine-driven pumps that raise the propellants used therein topressures high enough for injection into a combustion chamber, hasrequired specialized ducting that can, inter alia, accommodate assemblymisalignments, thermal induced defections and both pressure- andvibration-induced loads. Early rocket engines typically operated atcombustion chamber pressures of less than 1,000 pounds per square inch(psi), which required pump discharge pressures of less than 2,000 psi.For these applications, ducting, including tied bellows and braidedhoses adapted from the aircraft engine and petro-chemical industries,were utilized to accommodate the aforementioned misalignment anddeflections.

However, as combustion chamber pressures were increased from less than1,000 psi to greater than 3,000 psi and closed cycle engines wereintroduced, a need for propellant ducts operating at up to 8,000 psi attemperatures as low as −400° F. and hot gas ducts operating at up to6,000 psi at temperatures as high as 1,200° F. were established. The useof tied bellows or braided hoses are not feasible at these operatingconditions, so solid wall ducts possessing sufficient length androuting, and flexible enough to accommodate the deflections wereutilized. The excessive weight of the complex ducting created the needfor flange joints that could accommodate assembly misalignments andreact to the pressure- and vibration-induced loads without leakage atthe extreme operating conditions.

SUMMARY OF THE INVENTION

The present invention discloses a spherical flange assembly forovercoming the above-stated disadvantages, while also accommodating thepreferred operating conditions listed herein. A spherical flangeinterface, such as that disclosed below, preferably allows for asignificant amount of angular misalignment. Incorporating the sphericalflange apparatus at both ends of a duct accommodates both angular andoffset misalignment. This results in an easier assembly of enginecomponents and lower resultant loads which, in turn, makes for a morereliable joint due to better sealing conditions at the spherical flangeinterface. Additionally, the spherical flange of the present inventionaccommodates the misalignment of high pressure ducts, thereby reducingmisalignment loads, decreasing engine weight and facilitating assembly.

Misalignment of adjacent surfaces is allowed by providing a shape thatpermits joining the adjacent surfaces. More specifically, a spherical,convex surface is machined in the heel portion of one flange, protrudingfrom the structural surface. Into this heel portion, a seal groove ismachined that will receive a seal, either a packing or apressure-assisted seal. The pressure-assisted seal can have an unevenleg shape that can pick up the spherical surface shape, or it can bemade of differing glands. A matching spherical, concave surface ismachined into the mating interface flange, also known as the seatportion. Sufficient clearance is left between the flange portions whenthe spherical interfaces are engaged to allow them to rotate for thepredetermined angular misalignment. Bolts are then set in holescorresponding to the size of the clearance between the flange portions,with spherical washer sets under the bolt head and nut, thus providingbolt alignment consistent with the flange motion. The bolts are disposedon the apparatus in a uniform manner. This process precludes separationat the seat-to-heel interface when pressure and other operating loadsare applied.

To this end, a spherical flange assembly is disclosed. The sphericalflange assembly comprises a seat member, a heel member, a seal gland andat least one nut and bolt assembly. The seat member includes a concaveportion. The heel member includes a convex portion and a seal glandopening. The seal gland is disposed within the seal gland opening.

A better understanding of the objects, advantages, features, propertiesand relationships of the present invention will be obtained from thefollowing detailed description and accompanying drawings, which setforth an illustrative embodiment and which are indicative of the variousways in which the principles of the present invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference may be had tovarious embodiments, as shown in the following drawings, in which:

FIG. 1 illustrates a cross-sectional view of a spherical flangeinterface assembly, manufactured in accordance with the presentinvention;

FIG. 2 illustrates a cross-sectional view of the spherical flangeinterface assembly of FIG. 1;

FIG. 3 illustrates a cross-sectional view of the seat member of thespherical flange assembly of FIG. 1;

FIG. 4 illustrates a cross-sectional view of the heel member of thespherical flange assembly of FIG. 1; and

FIG. 5 illustrates an embodiment of the spherical flange interfaceassembly of FIG. 1, manufactured in accordance with the presentinvention and misaligned 2 degrees.

DETAILED DESCRIPTION OF THE PRESENTLY-PREFERRED EMBODIMENTS

Due to the inherent tolerance variability of hardware, flangemisalignments can occur during the installation of mating components fora liquid-propellant rocket engine. Further, these flange misalignmentscan include axial, lateral and/or angular offsets. If thesemisalignments are high, they can import significant loads into the twomating components, which can lead to failure. To address this flangemisalignment issue, a spherical flange assembly was developed thatallows for misalignment yet reduces imparted loads, while at the sametime provides sufficient sealing against leakage. The design of thepresent invention was tested to evaluate and compare performanceparameters, such as, for example, misalignment and leakage. During thetesting, the environmental conditions ranged from −100 to +400 degreesFahrenheit (° F.), with 1000 to 6000 pounds per square inch (psi)pressure being applied to the spherical flange assembly.

Referring to the Figures, and in particular FIG. 1, which illustratesone embodiment of the present invention, spherical flange assembly 10 isillustrated in cross-sectional form. As illustrated in FIG. 1, sphericalflange assembly 10 comprises, generally, seat member 12, heel member 14,bolt assembly 16 and seal gland 18. It is to be understood that bothseat member 12 and heel member 14 can extend away from the interfaceregion, shown in FIG. 1, for any preferred distances.

As can be understood from FIGS. 1-4, seat member 12 is preferablyspherical in cross-sectional shape; that is, seat member 12 preferablyis disposed uniformly and circumferentially about axis 20. Additionally,seat member 12 includes a concave portion; this portion will bedescribed in greater detail below. Preferably, seat member 12 alsopossesses seat member duct radius, R_(SD), and seat member sphericalradius, R_(SS). Seat member duct radius, R_(SD), corresponds to theradius of the inside of seat member 12, as described more fully below.

In a preferred embodiment, seat member 12 is made of Inconel 718™, whichis a high-strength nickel-based alloy capable of containing theoperating pressure and loads at the temperature extremes experienced byspherical flange assembly 10. However, it is nevertheless contemplatedthat seat member 12 may be made of any ducting material, such as, forexample, aluminum alloys, stainless steels, nickel base alloys, highstrength superalloys, titanium alloys or any composite thereof,depending on the application pressure and temperature.

Seat member 12 itself is divided into three portions: seat duct portion22, concave seat interface portion 24 and seat flange connection portion26. Seat duct portion 22 contains channel 28. It is through channel 28that gas or liquid flows from seat member 12 to heel member 14; that is,in a direction such that no forward step protrudes into the flowstreamwhen misaligned (as referenced by the arrow extending from Ref. No. 28).Concave seat interface portion 24 is the portion of seat member 12 whichcomes into contact with the corresponding interface portion from heelmember 14. Finally, seat flange connection portion 26 allows seat member12 to be conjoined with heel member 14, through the use of nut and boltassembly 16.

To facilitate the joining of seat member 12 with heel member 14,disposed within seat flange connection portion 26 of seat member 12 area plurality of openings 30. Preferably, each of the plurality ofopenings 30 are bored, drilled or otherwise cut through seat connectionportion 24 of seat member 12. Further, each of the plurality of openings30 are aligned, in both number and spacing, with a plurality of openings46 in the heel flange connect portion 42 of heel member 14.

As illustrated by FIGS. 1-4, channel 28 is defined by inside surface 34.Inside surface 34 of channel 28, as shown, also is disposed uniformlyabout axis 20. Thus, consequently, inside surface 34 of channel 28represents a constant flow area of seat duct portion 22 of seat member12.

Like seat member 12, heel member 14 is preferably also spherical incross-sectional shape, also being disposed uniformly andcircumferentially about axis 20, the same axis about which seat member12 is disposed. Preferably, heel member 14 also possess heel memberspherical radius, R_(HS). Heel member spherical radius, R_(HS), whichcorresponds to the radius of the conveyance of heel member 14, ispreferably approximately 1.5 to 2.5 times heel member duct radius,R_(HD), which corresponds to the radius of the inside heel member 12, asdescribed more fully below. This ratio between heel member sphericalradius, R_(HS), and heel member duct radius, R_(HD), of heel member 14serves to preferably accomplish approximately a 45° nesting interface ofheel member 14 into seat member 12. Alternatively, heel member 14 maycomprise any other spherical radius-shaped device that can neverthelessrealize the objects of the present invention.

It should be noted that axis 20 is common to both seat member 12 andheel member 14. Further, seat member duct radius, R_(SD), heel memberduct radius, R_(HD), seat member spherical radius, R_(SS) and heelmember spherical radius, R_(HS), are all based from points located alongaxis 20. As a result, in some instances, seat member duct radius,R_(SD), and heel member duct radius R_(HD), preferably comprise equalvalues. It should also be noted that heel member spherical radius,R_(HS), and seat member spherical radius, R_(SS), preferably comprisethe same length. This is because the curvature of heel member 14 isequal to the curvature of seat member 12.

In a preferred embodiment, heel member 14 is also made of Inconel 718,which is a high-strength nickel-based alloy capable of containing theoperating pressure and loads at the temperature extremes experienced byspherical flange assembly 10. However, it is nevertheless contemplatedthat heel member 14 may be made of any ducting material, such as, forexample, aluminum alloys, stainless steels, nickel base alloys, highstrength superalloys, titanium alloys or any composite thereof,depending on the application pressure and temperature.

Also similar to seat member 12, heel member 14 itself is also dividedinto three portions: heel duct portion 38, convex heel interface portion40 and heel flange connection portion 42. Heel duct portion 38 containschannel 44. Like channel 28, it is through channel 44 that gas or liquidis permitted to pass from seat member 12 to heel member 14 (again, referto the direction of the arrow extending from Ref. No. 44). Convex heelinterface portion 40 is the portion of heel member 14 which comes incontact, through, preferably, nesting, with the corresponding portionfrom seat member 12. Finally, heel flange connection portion 42 allowsheel member 14 to be conjoined with seat member 12, through the use ofnut and bolt assembly 16.

To facilitate the joining of seat member 12 with heel member 14,disposed within heel flange connection portion 42 of heel member 14 area plurality of openings 46. Preferably, each of the plurality ofopenings 46 are bored, drilled or otherwise cut through heel connectionportion 42 of heel member 14. Further, each of the plurality of openings46 are aligned, in both number and spacing, with the plurality ofopenings 30 in the seat flange connect portion 26 of seat member 12.

As illustrated by FIGS. 1-4, channel 44 is defined by inside surface 50.Inside surface 50 of channel 44, as shown, also is disposed uniformlyabout axis 20. Thus, consequently, inside surface 50 of channel 44 ispreferably a constant flow area of heel duct portion 38 of heel member14.

As channel 44 approaches convex heel interface portion 40, insidesurface 50 of channel 44 is beveled outward, as shown by referencenumeral 70. The purpose for the beveling 70 of inside surface 50 ofchannel 44 is selected to preclude a forward facing step from protrudinginto the flow stream with the maximum prescribed angular misalignment.

Additionally disposed within heel member 14 is seal gland opening 54. Asillustrated in FIGS. 1-4, seal gland opening 54 is disposed within firstheel interface portion 40 of heel member 14. Seal gland opening 54 ispreferably configured to receive seal gland 18. Seal gland 18 ispreferably used to provide a zero leakage seal between seat member 12and heel member 14. Preferably, seal gland 18 may comprise an o-ring forroom temperature application or a metal pressure actuated seal withappropriate coating for cryogenic or hot gas applications.

As illustrated by FIG. 2, width 66, preferably specified in degrees, ofconvex heel interface 40 is preferably greater than width 68 of sealgland opening 54, also preferably specified in degrees, plus two timesthe degrees of a predetermined allowable misalignment. This is such thatseal gland 18 will always be seated on the spherical surface of convexheel interface portion 40 when spherical flange assembly 10 ismisaligned.

As illustrated in FIG. 1, and part of spherical flange assembly 10 isbolt assembly 16. As illustrated, bolt assembly 16 comprises bolt 56,bolt spherical washer 58, nut 60 and nut spherical washer 62. Each boltassembly 16 are disposed within two of the plurality of openings 30, 46.In operation, when each bolt assembly 16 is installed within one of theplurality of openings 30, and a corresponding opening 46, bolt assembly16 is tightened, thereby nesting heel member 14 into seat member 12.Each element of bolt assembly 16 comprises elements commonly known inthe art, although it is preferred that each element comprises compatiblestrength materials to permit preloading spherical flange assembly 10with sufficient preload to preclude separation at the nested interfacesof heel member 14 and seat member 12 at maximum operating conditions.

Further, each of the plurality of openings 30, 46 are configured in amanner to receive bolt 56 of bolt assembly 16. That is, each of theplurality of openings 30, 46 are of a diameter large enough to permitthe prescribed angular misalignment without binding bolt 56 of boltassembly 16. It is further preferred that the inside surfaces 32, 48 ofeach of the plurality of openings 30, 46, respectively, comprise asmooth, unthreaded surface to allow bolt 56 of bolt assembly 16 to passthrough each of the plurality of openings 30, 46 and be retained by nut60 of bolt assembly 16.

FIG. 5 illustrates spherical flange apparatus 10 in operation. Referringto FIG. 5, heel member 14 is illustrated as being misaligned from seatmember 12. The axis of seat member 12 is illustrated as referencenumeral 72, while the axis of heel member is shown as reference numeral74. The angle of deflection between the seat member 12 and the heelmember 14 is illustrated by α. As can be seen from FIG. 5, althoughthere is misalignment between seat member 12 and heel member 14,spherical flange assembly 10 does not cause leakage of any gas or liquidcontained therewith. Also illustrated in FIG. 5 is an axial space 76.Axial space 76 is provided between seat member 12 and heel member 14 topermit a predetermined amount of angular misalignment by rotating on thenested spherical interface without bottoming on the flange faces. Alsoshown in FIG. 5 is the spacing between bolt assembly 106 and theplurality of openings 30, 46.

While specific embodiments of the present invention have been describedin detail, it will be appreciated by those skilled in the art thatvarious modifications and alternatives to those details could bedeveloped in light of the overall teachings of the disclosure.Accordingly, it will be understood that the particular arrangements andprocedures disclosed are meant to be illustrative only and not limitingas to the scope of the invention, which is to be given the full breadthof the appended claims and any equivalents thereof.

1. A spherical flange assembly for an engine, comprising: a seat memberhaving a concave portion; a heel member having a convex portion in matedassociation with the concave portion, wherein the heel member is rigidlyand removably connected to the seat member along approximately 45 degreenested interface formed by the concave portion and the convex portion;and a seal disposed in a three-sided seal groove, wherein thethree-sided seal groove is formed in the heel member along the convexportion; wherein the concave portion begins at the internal radius of afirst duct and wherein the convex portion begins at the internal radiusof a second duct, wherein the first duct is integrally formed as part ofthe seat member and the second duct is integrally formed as part of theheel member.
 2. The spherical flange assembly of claim 1, wherein theseat member further comprises a first flange having a plurality of firstapertures and wherein the heel member further comprises a second flangehaving a plurality of apertures, wherein the plurality of firstapertures and the plurality of second apertures are configured toreceive a plurality of fasteners for rigidly and removably connectingthe heel member to the seat member along the approximately 45 degreenested interface.
 3. The spherical flange assembly of claim 1, whereinthe convex portion of the heel member comprises a spherical radius ofapproximately 1.5 to 2.5 times the internal radius of the second ductand wherein the concave portion of the seat member comprises a sphericalradius substantially equal to the spherical radius of the convexportion.
 4. The spherical flange assembly of claim 1, wherein fluid orgas inside the first and second ducts during operation of the engineimproves the effectiveness of the seal to insure essentially zeroleakage past the seal.
 5. The spherical flange assembly of claim 1,wherein the spherical flange assembly is configured to convey a fluidcomprising a pressure of up to 8000 psi and a temperature as low asminus 400° F. during operation of the engine without leakage of thefluid past the seal.
 6. The spherical flange assembly of claim 1,wherein the spherical flange assembly is configured to convey a gascomprising a pressure of up to 6000 psi and a temperature of up to 1200°F. during operation of the engine without leakage of the gas past theseal.
 7. The spherical flange assembly of claim 1, wherein an amount ofangular misalignment is permitted between the seat member and the heelmember, the amount of angular misalignment comprising no more thanone-half the difference between a first angle defined by a central angleof the concave portion and a second angle defined vy a central angle ofthe three-sided seal groove opening, wherein the first angle and thesecond angle have a common vertex.
 8. A spherical flange assembly,comprising: a seat member comprising a concave portion defining a firstarc length; a heel member comprising a convex portion defining a secondarc length, wherein the heel member is rigidly and removably connectedto the seat member along an approximately 45 degree nested interfaceformed by the concave portion and the convex portion, wherein the secondarc length nests entirely within the first arc length when the sphericalflange assembly is nominally aligned; and a seal disposed along withapproximately 45 degree nested interface in an annular seal groovecomprising two opposing side walls and a bottom.
 9. The spherical flangeassembly of claim 8, wherein the seal groove is disposed approximatelymidway along the convex portion.
 10. The spherical flange assembly ofclaim 8, wherein the seal groove is formed in the heel portionapproximately midway along the convex portion.
 11. The spherical flangeassembly of claim 8, wherein an amount of angular misalignment ispermitted between the seat member and the heel member, the amount ofangular misalignment comprising no more that one-half the differencebetween a first angle defined by a central angle of the first arc lengthand a second angle defined by a central angle of the seal grooveopening, wherein the first angle and the second angle have a commonvertex.
 12. A spherical flange assembly, comprising: a seat membercomprising a concave portion defining a first arc length; a first flangehaving a plurality of first apertures; and a first duct, wherein theconcave portion, the first flange, and the first duct are integrallyformed as part of the seat member; and a heel member comprising a convexportion defining a second arc length; a second flange having a pluralityof second apertures; and a second duct, wherein the convex portion, thesecond flange, and the second duct are integrally formed as part of theheel member, wherein the heel member is rigidly and removably connectedto the seat member along an approximately 45 degree nested interfaceformed by the concave portion and the convex portion, wherein the secondarc length nests entirely within the first arc length when the sphericalflange assembly is nominally aligned, wherein the plurality of firstapertures and the plurality of second apertures are configured toreceive a plurality of fasteners for rigidly and removably connectingthe heel member to the seat member along the approximately 45 degreenested interface, and wherein each of the plurality of fastenerscomprise a nut, a bolt, a nut spherical washer, and a bolt sphericalwasher.
 13. A spherical flange assembly, comprising: a seat member,comprising a concave portion; a first flange having a plurality of firstapertures; and a first duct, wherein the concave portion, the firstflange, and the first duct are integrally formed as part of the seatmember; a heel member, comprising a convex portion; a second flangehaving a plurality of second apertures; a second duct; and a seal groovedisposed along the convex portion for receiving a seal, wherein theconvex portion, the second flange, and the second duct are integrallyformed as part of the heel member, wherein the seal groove is annularand comprises two opposing side walls and a bottom, and wherein the heelmember is rigidly and removably connected to the seat member alongapproximately 45 degree nested interface formed by the concave portionand the convex portion.
 14. A spherical flange assembly, comprising: aseat member, comprising a concave portion; a first flange having aplurality of first apertures; and a first duct, wherein the concaveportion, the first flange, and the first duct are integrally formed aspart of the seat member; a heel member, comprising a convex portion; asecond portion; a second flange having a plurality of second apertures;a second duct; and a seal groove disposed approximately midway along theconvex portion for receiving a seal, wherein the convex portion, thesecond flange, and the second duct are integrally formed as part of theheel member; and wherein the heel member is rigidly and removablyconnected to the seat member along an approximately 45 degree nestedinterface formed by the concave portion and the concave portion.